FWIW, I dunno what cream you're using, or what brush for that matter, But I've given myself a lot of fury over improper cream whipping, Start out with NO water, just the bare minimum in the brush, and whip the cream out as much as you can, until it's either a very flat paste and won't go anywhere, or it actually starts to build lather... Once it's building dry lather, add just a tiny bit of water, and whip a lot... The longer you whip the better.
You may know all of this already, but I wish someone had told it to me in blunt terms - No water to start with, VERY VIGOROUS whipping for a good while before adding water.
Hope I helped, or at least didn't harm :P
Cheers,
Jeremy